Common Mode Choke Coils / Balun Transformers

Applications of Baluns

In a RF balun transformer, one pair of terminals is balanced, that is, the currents are equal in magnitude and opposite in phase. The other pair of terminals is unbalanced; one side is connected to electrical ground and the other carries the signal. Balun transformers can be used between various parts of a wireless or cable communications system. Some common applications denotes as following:

  • Television receiver (Balanced) - coaxial cable network or Coaxial antenna system (Unbalanced)
  • FM broadcast receiver (Balanced) - Coaxial antenna system (Unbalanced)
  • Dipole antenna (Balanced) - Coaxial transmission line (Unbalanced)
  • Parallel-wire transmission line (Balanced) - Coaxial transmitter output, or Coaxial receiver input (Unbalanced)

Token's baluns provide impedance transformation in addition to conversion between balanced and unbalanced signal modes. Most television and FM broadcast receivers are designed for 300-ohm balanced systems, while coaxial cables have characteristic impedances of 50 or 75 ohms. Impedance-transformer baluns with larger ratios are available and used to match high-impedance balanced antennas to low-impedance unbalanced wireless receivers, transmitters, or transceivers.

Download General Info. of Balun Transformer in PDF file.

Download Entire Common Mode SMD EMI Filters & RF Balun Transformers Catalogue PDF file.

Common mode filter for signal line

ThumbnailSMD Coils type and description DCR (Ω) Current (A)

  • 1 Low Profile Common Mode Chokes (TCPWCS160808/201209) 10 ~ 160 0.2 ~ 0.5 Token (TCPWCS) series common mode chokes offer just 1.6 x 0.8 mm (0603) and 2.0 x 1.2 mm (0805), with a maximum height of 0.8mm and 0.9 mm, making them the lowest-profile common mode chokes available. The (TCPWCS) series comes with very low DCR (0.25 to 0.80 Ohms) and current ratings up to 500 mA. Wide range impedance values are available to meet specific design requirements.
    TCPWCS Series - PDF

  • 2 Common Mode Choke Coils for Automotive (TCPWCH-4532AU) 600 ~ 5800 0.15 ~ 0.25 SMD common mode choke coils (TCPWCH-4532AU) series is primarily designed for automotive networking applications. such as automotive ethernet, FlexRay, and CAN-Bus. Of course, ethernet is already the firmly established networking protocol for computers, peripherals, communication devices, and multimedia.
    TCPWCH-4532AU Series - PDF

  • 3 Common Mode Chokes For USB, IEEE 394, Lan Interface
    12 ~ 5800 0.2 ~ 4.0 Token Electronics offers SMD Common Mode Inductors & EMI Filters (TCPWCH) in standard 0805, 1206, 1810, and 1812 size, with a maximum height of 1.2 mm, 2.0 mm, 2.2 mm, and 2.8 mm making them low profile common mode chokes available. Common mode chokes (TCPWCH) are used in order to filter common mode electromagnetic interference (EMI) currents without de-rating under high currents and without causing signal degradation.
    TCPWCH Series - PDF

  • 4 Common Mode Chokes for High Speed Signal Filtering
    25 ~ 90 0.40 ~ 0.42 Token (TCPWCH-1210HS/2012HS) Series SMD Common Mode Choke Coils are for high-speed and ultra-high-speed differential signal lines such as LVDS, IEEE1394//FireWire, USB, etc. The chip type (TCPWCH-1210HS/2012HS) series provides EMI suppression in case sizes 0504, and 0805.
    TCPWCH-1210HS/2012HS Series - PDF

  • 5 Common Mode Filters & Chokes for HDMI (TCPWCH-2012HD) 40 ~ 120 0.37 ~ 0.40 HDMI port has been widely used in all kinds of A/V equipments with the development of HD & full HD video technology. HDMI provides ultra high transfer rate and supports hot plug and play technology. According to the latest HDMI1.4 specification, HDMI provide a max transfer rate of 4.8Gbps, which could well address the need of full HD video transmission.
    TCPWCH-2012HD Series - PDF

  • 6 Balun Transformers for Digital TV Tuners, WBL (TCPWCH-2012BL) 50 ~ 75 0.2 ~ 0.3 Token (TCPWCH-2012BL) has commercialized chip transformers (balun transformers), which are used to convert between unbalanced-balanced signals in the antenna inputs of TV tuner circuits for terrestrial digital broadcast compatible compact mobile devices.
    TCPWCH-2012BL Series - PDF

  • 7 RF Balun Transformers Frequency Mixer (TCB4F) - - Token SMD RF Balun Transformers Frequency Mixer (TCB4F) is primarily designed for choking power lines and conform to the RoHS compliant and Lead-free. SMD (TCB4F) can be customed designs and tighter tolerances available on request.
    TCB4F Series - PDF

  • 8 Transformer for Frequency Mixer (TCB5F) - - Bottom portion pinastre are generally finish manufactured to let for straight installation on PCB (printed circuit board). Excellent for use as double balanced mixers, broad band transformers, transistors as well as impedance transformation.
    TCB5F Series - PDF

  • 9 RF Balun Transformers for Frequency Mixer (TCB5FL) - - Application of RF balun transformer specific designs also available including different inductance values and Q specifications adjusted to frequency requirements. Base pins are end proccessed to allow direct mounting on PCB. Ideal for use in double balanced mixers, and as broad band transformers, transistors and for impedance conversion.
    TCB5FL Series - PDF

Common mode filter for power line

ThumbnailSMD Coils type and description DCR (Ω) Current (A)

What is Balun Transformer?

Balun is name of device that can be like a common mode choke, unbalance to balance transformer, or a step up or down transformer.
Balun is an acronym of BALanced UNbalanced, it's used to convert an unbalanced signal to a balanced one or vice versa.
A balun transformer is a device that:

  • joins a balanced line (one that has two conductors, with equal currents in opposite directions, such as a twisted pair cable).
  • to an unbalanced line (one that has just one conductor and a ground, such as a coaxial cable).

Baluns isolate a transmission line and provide a balanced output. A typical use for a balun is in a television antenna.

Balanced: A method of transmitting signals using two signal lines. One line carries the source signal; the other carries a signal of opposite phase (antiphase).
Unbalanced: A method of transmitting signals using one signal line, with a ground line providing a reference potential.

Why Use a Balun?

Baluns are used for two primary reasons:

  • One : Eliminate “common mode current” on the transmission line.
  • Two : Matching antenna impedance to the transmission line.

Insertion Loss (dB)

Loss due to transmission from primary dot port to secondary dot port and secondary port. Most balun transformers are symmetrical through their central horizontal axis, therefore, an input can be applied at the primary dot port or the primary port with differential outputs at the secondary dot and secondary ports.

Basics of Broadband Transformers

There are two kinds of broadband transformers. One is known as a conventional type, which has separate primary and secondary windings, as do power and audio transformers. The other type is called a transmission-line transformer. It is believed that the latter variety is the most efficient of the two. Transmission-line transformers are wound with twisted or parallel windings and produce specific integers of impedance transformation, such as 4:1, 9:1, and 16:1. Conventional transformers permit you to obtain any transformation ratio you need.

Download What is Balun Transformer in PDF file.